Won't start, carburetor?

[blab]

Hi,

after sitting for a year or so the engine won't start.

Looks like the ignition works. I had test sparks to ground from the coil and also sparks from a single spark plug wire.

There is fuel at the fuel pump and when I remove the fuel line at the carburetor I get this amount after cranking for 10 seconds (estimated):



Yes, it's fuel. :-)

I think that's enough? When I spray start spray into the carb the engine will fire for a short moment.

Does this mean it's the carburetor? Engine ran last time until I switched it off.

The carb is an early nineties 625cfm Carter AFB. Seems to be an Edelbrock, sold under the Carter label:



Beside cleaning/rebuilding the carb I'm out of ideas.

Not sure if this is important but the engine ran kind of rough until it warmed up (when it ran).

[Alan H. Tast]

The carb is an early nineties 625cfm Carter AFB. Seems to be an Edelbrock, sold under the Carter label:

Quite the opposite: The Carter AFB came first; Edelbrock secured licensing to manufacture it, but I don't think they did this until after the mid-2000s.

The factory shop manual has testing procedures for pump output: if you don't have a copy of the shop manual, I urge you to get one NOW. If not for yourself, then for use by a mechanic who may work on your car in the future.

[gyoungwolf]

HI. The short answer is Probably. My 15 years experience rebuilding carbs says that if it looks that bad on the outside, there is probably corrosion and deteriorated rubber or gasket material clogging things up on the inside. Carter used some cheap recycled aluminum and zinc material for many years until they starting losing sales because of it. Don't know if it is just a lighting problem, but you should have some nice clear, fresh premium fuel to the carb. II would also recommend checking the condition of the spark plugs while you are at it.
Grant

[mainstreetprod]

I don't think the fuel pump is up to par. I found a spec on an electric fuel pump, 140 gallons per hour. At that rate, in 10 seconds it should fill a 1 gallon gas can 1/3 full ! Mechanical fuel pumps probably don't produce that volume, but they do pump a lot more than in your cup! But before replacing the pump, make sure there is no blockage in the filter, fuel line or tank inlet filter sock. If your gas gauge doesn't work, might be a good time to pull the sender unit and check the filter sock at the same time. I pulled mine and it looked terrible.

[blab]

Thanks for the replies.

The factory shop manual has testing procedures for pump output: if you don't have a copy of the shop manual, I urge you to get one NOW. If not for yourself, then for use by a mechanic who may work on your car in the future.

Yes, I have it. I just thought it wouldn't apply because I don't have an Autolite.

HI. The short answer is Probably. My 15 years experience rebuilding carbs says that if it looks that bad on the outside, there is probably corrosion and deteriorated rubber or gasket material clogging things up on the inside. Carter used some cheap recycled aluminum and zinc material for many years until they starting losing sales because of it. Don't know if it is just a lighting problem, but you should have some nice clear, fresh premium fuel to the carb. II would also recommend checking the condition of the spark plugs while you are at it.
Grant

I'll rebuild the carb. Spark plugs are kind of new. The fuel color in the foto looks correct. Any idea where this might come from? Water?

I found a spec on an electric fuel pump, 140 gallons per hour. At that rate, in 10 seconds it should fill a 1 gallon gas can 1/3 full ! Mechanical fuel pumps probably don't produce that volume, but they do pump a lot more than in your cup! But before replacing the pump, make sure there is no blockage in the filter, fuel line or tank inlet filter sock. If your gas gauge doesn't work, might be a good time to pull the sender unit and check the filter sock at the same time. I pulled mine and it looked terrible.

The mechanical pump depends on the engine speed which is very slow when starting. Still, I'll replace the pump. Thanks for the tip with the filter sock. Mine didn't look well when I replaced the floater of the sender unit.

[blab]

Today I removed the fuel hose at the carb to replace a clamp. A lot of fuel spilled out under a lot of pressure.

After that I ran the starter again for about 30 secs (not continuous) to build up new pressure. Then opened the choke plate and looked for fuel discharge when pulling the accelerator linkage:



It should discharge from the brass nozzles inside the venturis? Nothing came out there. So even with the high fuel pressure at the hose, the carb looks completely dry (from the outside).

[mainstreetprod]

Accelerator pump plunger is probably shot. I was just reading that even 10% ethanol in fuel can do that to carb parts, fuel pump diaphrams, etc.

[blab]

I think i found it. During disassembly it turned out that the floater needles were stuck in the closed position. Carb was without fuel, floater chambers were dry.

The brass triangles in the lower left and lower right:



The accelerator pump plunger wasn't broken. Didn't look good either though.

[sseebart]

I think i found it. During disassembly it turned out that the floater needles were stuck in the closed position. Carb was without fuel, floater chambers were dry.

The brass triangles in the lower left and lower right:



The accelerator pump plunger wasn't broken. Didn't look good either though.

Nice work. Looks like you'll be back in business shortly. One additional step to consider: unless there was some kind of stabilizer in the fuel, you may want to consider siphoning it out and replacing with fresh. Modern gas goes stale pretty quickly.

~Steve

[blab]

unless there was some kind of stabilizer in the fuel, you may want to consider siphoning it out and replacing with fresh. Modern gas goes stale pretty quickly.

No stabilizer. What happens with the fuel? Can I use it if the engine will run? Fuel tank is more than a quarter full. Getting rid of that would require some planning.

[sseebart]

No stabilizer. What happens with the fuel?

I understand that the volatiles evaporate rapidly. What remains burns poorly & can gum up the carburetor.

With the tank only one quarter full, you could probably dilute the old gas with new. 'Course if that doesn't work, then you have a whole tank to dispose of.

~Steve

[60fore]

Blab, I see you're located in Germany. Does the fuel there contain ethanol? Ethanol blended fuels are subject to something called phase separation, which as mentioned causes all sorts of nasty side effects. Here's an article on phase separation:

http://www.franklinfueling.com/media/39 ... 12-web.pdf

[gyoungwolf]

Your inlet assemblies are aftermarket units that have a spring-loaded inlet needle. While this is a good part to use in off-road applications, it is not, as you have found, necessarily a good idea on limited use vehicles as the needle is lighter and there is no way to use the little clip that normally pulls in down out of the seat. This often results in stuck needles. I recommend going back to a stock one-piece needle. It can be used with the same seat, but my guess is that it might be bigger than stock as it is marketed as a performance part. The carb looks a LOT better on the inside :-).
Grant

[blab]

Fuel: thanks for the explanations. Our "super" fuel should contain up to 5% ethanol. That's the maximum, usually it should be between 0% and 3%. Kind of difficult to google.

Grant, I have replacement one-part needles and seats in the rebuild kit. However, the new Edelbrock ones are marked '42' while the original ones are marked '38':



Can I use the new ones anyway?

[gyoungwolf]

HI. The nos. probably mean something, but it's not the size. The aftermarkets are usually .089" while the ones in our 4100 series carbs are .098" .I'm sorry, but I don't know off hand what the Carter carb calls for, but the kit is probably correct. They didn't use to flow rate their carbs, but they were usually 525 or 625 cfm. (You don't really need those little mesh baskets as you should have a good inline fuel filter and the mesh would only catch non-dissolved stuff that couldn't get past it, and they interfere with the fuel flow characteristics).